The Fe-Cr-Co type magnet alloy is a Spinodal type alloy discovered in 1971 for the first time, which is known as a ductile magnet alloy. This alloy is rich in tenacity and capable of being processed by rolling, wire drawing, blanking and deep drawing in its solution heat-treated state.
This magnet alloy had originally a Co content of 17-23% by weight and showed magnetic characteristics only comparable with those of ALNICO 5. As a result of later research on alloying elements or components and heat treatment, however, a composition system comprising a reduced amount of Co ranging 5-15% by weight has been proposed and put to practical use, which exhibits magnetic characteristics equivalent to or better than those of ALNICO 5 or ALNICO 5DG. It is also known that the addition of minor amounts of Mo, W, Si, etc. enhances the magnetic characteristics and coercive force of such an alloy system.
Where the Fe-Cr-Co type magnet alloy is melted in the atmosphere and cast, if atmospheric nitrogen (N) enters the molten metals in the meantime, crystallization of a gamma phase takes place, leading to deterioration in magnetic characteristics. To prevent the crystallization of the gamma phase having a markedly adverse influence on magnetic characteristics, the addition of titanium (Ti) was found to be very effective. Usually titanium is added in an amount of about 1% by weight during melting. Fe-Cr-Co type magnet alloys having a low cobalt content, which are recently on the market, are manufactured on an industrial scale by melting in the atmosphere, taking advantage of the effect of Ti addition.